Strategies to improve the therapeutic ratio – increasing the dose to tumor and reducing the dose to normal tissues – continue to be investigated.

The physical properties of proton therapy allow for unique dose deposition with no exit dose, potentially reducing the dose to normal tissues, including the irradiated thoracic bone marrow.

The objective of this study was to determine if proton therapy can reduce the amount of bone marrow suppression in comparison to 3D conformal and intensity modulated radiation therapy (IMRT) in lung cancer patients treated with concurrent chemotherapy and radiation.

Methods

This was a single institution, nonrandomized, retrospective review of NSCLC patients treated at the M.D. Anderson Cancer Center from 2003 – 2008.

There were 132 patients: 67 in the proton arm and 75 in the 3D/IMRT arm.

The poorer overall survival in the 3D/IMRT arm merits further investigation and may reflect confounding limitations, such as increased number of patients with Stage IIIb disease and chemotherapeutic dose reductions in the photon arm.

The ongoing randomized controlled trial of proton versus photon therapy in patients with Stage III NSCLC should further clarify these issues.